1. Field of the Invention
The field of this invention relates to a concentricity measuring instrument for a fiberoptic cable end.
2. Description of the Related Art
Fiberoptic cables are flexible, elongated essentially transparent devices that are used for either image or data transmission with the light being propagated through the cable. The fiberoptic cable has a core with a refractive index higher than that of the surrounding cladding. Surrounding the cladding is what is called a jacket. The light is to be transmitted through the core with the cladding and jacket functioning to contain the light and not permit the light to be transmitted through the side of the cable.
Fiberoptic cables can be constructed of any desired length. Typically, these cables may be anywhere from a few inches in length to hundreds of feet in length. Quite often, it is required that a fiberoptic cable be connected to another fiberoptic cable with the light from the one fiberoptic cable to be transmitted through the other fiberoptic cable. Each fiberoptic cable has a core and this is where the light is being transmitted. The core of one fiberoptic cable must precisely align with the core of the other fiberoptic cable in order to obtain maximum efficiency of transmission of the light. Any misalignment, even as small as less than one micron, can cause a substantial reduction in the efficiency of the transmission of light and possibly even no transmission of light at all.
If a cut is transversely made through a fiberoptic cable and one was able to observe that cut surface, the core will be represented as a small centrally located circle generally only a few microns in diameter. Surrounding that core and integrally connected therewith is a cladding which is substantially greater in diameter than the core. Still further surrounding the cladding in most fibers in a concentric relationship is a jacket. The diameter of the jacket is frequently not greater than one-sixteenth or one-eighth of an inch. It is desirable to ascertain the concentricity of the core relative to the cladding and the jacket which will inform the technician the exact position of the core. This determining of the positioning of the core is at the time of manufacture of the cable. If it is determined that the core is off center beyond a certain tolerance, then that particular manufactured cable is rejected. When one cable end abuts against another cable end, the cores between the respective cable ends must be in precise alignment. At the present time, there is no known structure to clearly and easily observe the core relative to the cladding.
A concentricity measuring instrument for a fiberoptic cable end which utilizes a mounting block that is constructed of a plastic material that randomly disperses light. Formed within the mounting block is a through opening with this through opening being adapted to receive a fiberoptic cable end. The mounting block is attached to a ring with the ring having a light outlet window formed therein. Light is to be transmitted to the ring and emitted through the window into the block. The light within the block illuminates the cable end from the side. A microscope is then used to observe the cable end with the microscope being connected to software which then can calculate the position of the core relative to the cladding and the jacket of the fiberoptic cable and make a determination how far off precise center the core is relative to the cladding and the jacket.
A further embodiment of the present invention is where the previous apparatus utilizes a block constructed of epoxy resin and titanium dioxide particles
A further embodiment of the present invention is where the apparatus is constructed so that the through opening formed within the block is centrally mounted within the block.
A further embodiment of the present invention is where the previous apparatus is modified by the through opening including a cone-shaped enlargement within the through opening through which the observation by the microscope is to occur.
A further embodiment of the present invention is where the apparatus is defined to include a ring on which the block is mounted with this ring including an annular light outlet window through which the light is to be transmitted within the block.
A further embodiment of the present invention is where the apparatus is modified by the ring on which the block is mounted includes an annular light receiving chamber.
A further embodiment of the present invention is where the apparatus is modified by there being mounted on the block an iris which improves the contrast of the observation by the microscope.
A further embodiment of the present invention is where the just previous embodiment is modified by the iris being adjustable so as to vary the size of the aperture through the iris in order to maximize the observation by the microscope.
A further embodiment of the present invention relates to the method of ascertaining the concentricity of a core of a fiberoptic cable end which comprises the steps of placing the fiberoptic cable end within a block which is constructed to randomly disperse light, projecting of the light directly into the block with the light illuminating the cable end from the side of the cable end, observing of the cable end with the observation being able to detect the position of the core relative to the surrounding cladding and jacket and calculating the position of the core relative to the precise center of the cable.
A further embodiment of the present invention is where the method just described utilizes unfocused light from a non-coherent source.
A further embodiment of the present invention is where the basic method of the present invention utilizes a microscope in conjunction with an iris in making of the observation of the cable end.
A further embodiment of the present invention is where the method of the present invention requires placing of the cable end in a through hole formed within the block.
A further embodiment of the present invention is where the just previous embodiment is modified by centrally locating of the through hole within the block.
A further embodiment of the present invention is where the basic method of the present invention is modified by utilizing of a block that is constructed of an epoxy resin plus titanium dioxide particles.